The technical field generally relates to internal combustion engine technology. Initiatives within the United States and abroad have promoted the expanded use of biofuels as an alternative to petroleum-based blends owing primarily to the renewable character of the base biofuel stock. The variation in properties of biofuels and biofuel blends, with reference to petroleum-based fuels, results in differences in output NOx, particulate matter, fuel specific engine torque, and other responses of the engine. Accordingly, further technological developments are desirable in this area.